Did you know that the new Script Editor version 2 for Mac OS X (in beta as of this writing) uses unix linebreaks instead of mac linebreaks? This can cause problems if you use the constant "return" or write lines to a file expecting them to be mac linebreads like \r, instead, they may be \n. To deal with that in a few scripts, I've resorted to using ASCII character 10 (unix \n, newline, linefeed, LF) and ASCII character 13 (mac \r, carriage return, return, CR) to specify which I need.
(windows uses both charchaters together, CRLF, a carriage return with a line feed, or \r\n for each line break, so if you need windows or DOS line breaks, use "ASCII character 13 & ASCII character 10")